1. Field of the Invention
This invention relates to a process for determining the presence of a given antigen or antibody in a serum. More especially, this invention relates to a process for determining the presence of an antigen or antibody in a sample containing such antigen or antibody in the form of an immune complex. This invention is particularly concerned with determining the presence of antigen or antibody in a sample wherein said antigen or antibody exists in the form of an immune complex in small quantities (range pg to mg/ml).
2. Discussion of Prior Art
Immune complexes play a pathogenic role in many infectious, auto-immune and neoplastic diseases. (E. V. Barnett, D. W. Knutson, C. K. Abras, D. S. Chia, L. S. Young, M. R. Liebling; Circulating Immune Complexes; Their Immunochemistry, Detection, And Importance, ANN. INTERN. MED. 91, 430-440, 1979; J. L. Dienstag, A. K. Bhan, H. J. Alter, S. J. Feinstone, R. H. Purcell; Circulating Immune Complexes In Non-A, Non-B Hepatitis, LANCET 1, 1265-1267, 1979, J. R. Wands, E. Mann, E. Alpert: The Pathogenesis Of Arthritis, Associated With Acute Hepatitis B Surface Antigen-Positive Hepatitis: Complement Activation And Characterization Of Circulating Immune Complexes, J. CLIN. INVEST. 55, 930-936, 1975; V. E. Jones, E. Orlans: Isolation Of Immune Complexes And Characterization Of Their Constituent Antigens And Antibodies In Some Human Diseases: A Review, J. IMMUNOL. METHODS 44, 249-270 1981; R. C. Williams, Jr.: Immune Complexes In Human Diseases, ANN. REV. MED. 32, 13-28, 1981). Antigens corresponding to infectious agents, self-antigens and tumor antigens, respectively, may not be present in biological fluids in free form but only complexed with antibodies. Therefore, they may elude detection unless methods for isolation of the respective antigens from antibodies are developed. Although such separation techniques have been described (A. B. Pereira, A. N. Theofilipoulos, F. J. Dixon: Detection And Partial Characterization Of Circulating Immune Complexes With Solid Phase Anti-C3, J. IMMUNOL. 125, 763-770, 1980; R. Heimer, D. L. Glick, J. L. Abruzzo: The Detection Of Antigens In Immune Complexes; SCAND. J. IMMUNOL. 13, 441-446, 1981; V. E. Jones, E. Orlans: Isolation Of Immune Complexes And Characterization Of Their Constituent Antigens And Antibodies In Some Human Diseases: A Review, J. IMMUNOL. METHODS, 44, 249-278, 1981) they are useless from a practical point of view if many specimens need to be analyzed.
Although successful attempts to identify antigens within immune complexes without separating them from antibodies have been described, (R. Heimer, D. L. Glick, J. L. Abruzzo: The Detection Of Antigens In Immune Complexes, SCAND. J. IMMUNOL. 13, 441-446, 1981; V. E. Jones, E. Orlans: Isolation Of Immune Complexes And Characterisation Of Their Constituent Antigens And Antibodies In Some Human Diseases: A Review, J. IMMUNOL. METHODS, 44, 249-278, 1981; S. Husby, S. E. Svehag, H. Nielsen, N. Hiby, P. O. Schitz: Methodological Approaches To Antigen Identification In Soluble Immune Complexes; A Model Study, ACTA. PATH. MICROBIOL. SCAND. 89C, 255-260; C. Cunningham-Rundles: The Identification Of Specific Antigen In Circulating Immune Complexes By An Enzyme-Linked Immunosorbent Assay: Detection Of Bovine-.chi.-Casein IgG Complexes In Human Sera, EUR. J. IMMUNOL. 11, 504-509, 1981) such successes appear to be an exception and are generally not applicable for diagnostic purposes. Immune complexes containing infectious agents may retain infectivity and may thus become involved in the transmission of disease. Furthermore, circulating immune complexes may be involved in unfavorable modulation of the immune response leading to perpetuation of the disease. Therefore, the detection of medically significant antigens sequestered within immune complexes appears to be of great importance, and a necessary addition to many sensitive immunoassays which have been utilized in medical diagnosis during recent years.
It is an object of this invention, therefore, to provide a process for the detection of given antibodies or antigens in a sample where the antigens or antibodies are present in the form of an immune complex. It is especially desirable to provide a process whereby such antibodies or antigens can be detected in said samples even present in the form of an immune complex in concentrations less than 1 nanogram per milliliter.